Most suppressors of the <i>S</i>. <i>cerevisiae trm7Δ</i> growth defect map to PheRS subunits and all reduce activation of the GAAC response.

<p><b>(<i>A</i>) Each of 18 suppressors of the <i>trm7Δ</i> growth defect examined has reduced GAAC induction.</b> Strains were grown in rich media at 30°C to mid-log phase, and mRNA was isolated and analyzed for relative <i>HIS5</i> mRNA levels. <b>(<i>B</i>) Overproduction of both subunits of PheRS partially suppresses the <i>trm7Δ</i> growth defect.</b> WT or <i>trm7Δ</i> [<i>URA3 TRM7</i>] strains containing a high copy [2μ <i>LEU2</i>] plasmid expressing <i>FRS1</i>, <i>FRS2</i>, both, or neither as indicated under P_<i>GAL</i> control were grown overnight in S-Leu medium containing raffinose and analyzed by spotting to synthetic media containing 5-FOA, raffinose (raff), and galactose (gal), and incubated for 3 d at 30°C. Strains from the 5-FOA plate were then purified on the same medium, grown overnight in S-Leu medium containing raffinose and galactose, diluted, and spotted to rich (YP) media and minimal (S- leu) as indicated, and incubated for 3 d at 30°C. <b>(<i>C</i>) Overproduction of both subunits of PheRS reduces the GAAC induction in <i>trm7Δ</i> cells.</b> Strains containing a [<i>LEU2</i>] plasmid expressing <i>FRS1</i>, <i>FRS2</i>, both, or neither as indicated under P_<i>GAL</i> control were grown in S-Leu medium containing raffinose and galactose, and then mRNA was isolated and relative <i>HIS5</i> mRNA levels were determined.